[Q:] Sourcing authentic components

[Faros]

I always source components through authorized / trustworthy component providers from the US since I can't afford failures due to faulty components, I have a project that requires a switching regulator, I have chosen the TI  LM2596S-ADJ  priced at 1.88$ Qty. 1K.  . To my surprise, there are several Chinese sites links for the same part number priced at 0.1$ , the Qty is not an issue , he can ship 100 pc’s!!! the component list is long and diverged .

Do some members here have experience with such chips? how fake they are?  Give idea on its performance ?
Does anyone have a clue how on earth can the Chinese sell at such price tag? …     

[reksbg]

Probably they are not fake just didn't go through QA inspection. We got burnt few times with chips like that. For example MOS transistor from Infineon - it was original even the mask was original but the part didn't pass QA inspection and didn't have good switching parameters. Let's say the chinese manufacturer is subcontracted by Infineon to make 100000 chips. They make 200000 instead, 100000 go through the whole process and the other half not and then the chinese manufacturer sells them very cheap because they don't have the expenses Infineon has - R&D, marketing, distributor's discount etc. Another example - electrolytic capacitors 2200uF/63V. They start failing and when we opened them inside the big can you find smaller capacitor - 2200uF but just 35V . So stick with the US authorized distributors and don't bother ordering parts from China. You know what they say - if it is too good to be true probably it is .  $1.88 vs $0.1 is not giving you any room to think about it .

[Faros]

The chip is sold within a complete modular power supply priced at 2$ Qty 100.
http://www.banggood.com/Wholesale-DC-DC-LM2596-Converter-Buck-Adjustable-Step-Down-Regulator-Power-Module-1_2-35V-p-46754.html
The strange thing is that it has 100% positive user review from 5 user !!

[pickit2]

Does anyone have a clue how on earth can the Chinese sell at such price tag? …    

as reksbg says
You have a few things to think about, one the fakes these are down right fake /out of spec devices, radio shack used to sell packs of devices transistors remarked.
two new old stock, a plant has finished a order, and unused parts are no longer under control standards/ can't trace how they have been handled.
Then you have the reclaimed parts, scrap boards striped of components, I think I have bought some of these in the past.
Also they use china post, almost free to use, but they charge you $10 postage.

Look at what people say who have bought from them, I have a few sellers that don't charge till I have the items.
If they offer free post and small orders, buy a few days apart then you have a chance the item slips through customs & taxes are not charged at full rate, or not all.

[Faros]

@Pickit2
I am not a manufacturer myself, I design circuit for electronic products manufacturers. The completion of the design takes account of sourcing the best price / performance ratio of components as designed. I always keep in mind the cost of components during the design phase as I judge best designs as those which satisfy the cost saving factor among other design factors like performance, integrity … etc.
The problems associated with “out of specifications” component in design phase is painful, most likely they will not comply to SPICE models provided by semiconductor manufacturers and used in simulation. My designs are judged by ratio of failed / passed products over time. Promoting for Chinese component is not in my favor and I don't recommend it however I sometimes face this questions by some clients and I needed a practical answer out of speculations.   

[Ichan]

Try them first, some of them 90% as good as the original - some is just burnt on 20% of the power rating.

I use china made Lm2576 at 2A with no problem, but the IRFZ44 mosfet gets very hot only at 2A while the original one stay cool at 10A.

-ichan.

[Sideshow Bob]

Another example - electrolytic capacitors 2200uF/63V. They start failing and when we opened them inside the big can you find smaller capacitor - 2200uF but just 35V . So stick with the US authorized distributors and don't bother ordering parts from China. You know what they say - if it is too good to be true probably it is .  $1.88 vs $0.1 is not giving you any room to think about it .

I have seen pictures of this. But thought it was a some sort of student practical joke.

[DreamCat]

yeah, there are many guys has no conscience in china. and lack of supervision from government.
I also bought some defective chips，it cause project stalled.

[pickit2]

I have seen pictures of this. But thought it was a some sort of student practical joke.

wonder if it's a double bluff, I bet there is a tant cap inside the rubycon.

[EHHS1979]

This is a great topic, since it is getting much attention in my line of work.  The concern is "Counterfeit parts", and especially with parts no longer made.  You could get the very expensive Rochester reproductions, you will want to stay away from counterfeit parts, because most will fail, and if they don't fail specifications at room temperatures, try at the extreme temp ranges.  Burr Brown devices is a big target with counterfeiters.

[reksbg]

The one from the picture is easy to catch because it says 6800uF but inside is 2200uF. The receiving inspection guys will catch it with lust simple measurement. And I don't think the chinese manufacturer will spend the money for Rubycon part inside that is probably more expensive than the real noname 6800uF/50V capacitor  . Our subcontractor that assembles the pcbs bought 20000 pcs from a parts broker and when they tried to contact the chinese manufacturer there was no longer company like that

[Faros]

In my line of business I have found those who care about authentic components with near DATE CODE to insure flawless soldering as older components  are subject to rust which impact proper soldering on automated Pick’nPlace , on the other hand I have found those who care to spend great deal of time to reach the cheapest possible Chinese components and pray that products pass the warranty period.